Composite articles made by process for joining brass part and silicon carbide ceramic part

ABSTRACT

A process for joining a brass part and a silicon carbide ceramics part, comprising steps of: providing parts comprising a brass part, a silicon carbide ceramics part, an aluminum foil and a nickel foil; bringing surfaces of the silicon carbide ceramics part, the aluminum foil, the nickel foil and the brass part into contact in turn; applying a joining pressure between about 10 MPa and 40 MPa to the parts; heating the parts at a rate below 50° C./min when a temperature of the parts is below about 300° C.; when the temperature of the parts is above about 300° C., heating the parts at a rate of about 80° C./min˜200° C./min until to a joining temperature of about 550° C. to about 650° C., and maintaining the joining temperature between about 15 minutes and 40 minutes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to co-pending U.S. patentapplications U.S. Ser. No. 13/166,333, entitled “PROCESS FOR JOININGBRASS PART AND SILICONE CARBIDE CERAMICS PART AND COMPOSITE ARTICLESMADE BY SAME”, by Zhang et al. This application has the same assignee asthe present application and has been concurrently filed herewith. Theabove-identified applications are incorporated herein by reference.

BACKGROUND

1. Technical Field

The exemplary disclosure generally relates to a process for joining ametal part and a ceramic part, especially to a process for joining abrass part and an silicon carbide ceramics part, and an article made bythe process.

2. Description of Related Art

It is desirable to join brass parts and silicon carbide ceramics parts.However, due to the two material having very different values fordistinct physical and chemical properties, such as thermal expansion, itcan be difficult to join brass and silicon carbide ceramics usingtraditional bonding methods such as braze welding, fusion welding, andsolid diffusion bonding.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the exemplary process for joiningbrass part and silicon carbide ceramics part, and composite article madeby the process. Moreover, in the drawings like reference numeralsdesignate corresponding parts throughout the several views. Whereverpossible, the same reference numbers are used throughout the drawings torefer to the same or like elements of an embodiment . . . .

FIG. 1 is a schematic cross-sectional view of an example of a sparkplasma sintering device for implementing the present process.

FIG. 2 is a cross-sectional view of an exemplary embodiment of thepresent article made by the present process.

DETAILED DESCRIPTION

The process according to the present disclosure is generally implementedby a spark plasma sintering (SPS) device as illustrated in FIG. 1.

Referring to FIGS. 1 and 2, an exemplary process for joining a brasspart and an silicon carbide ceramics part may include the least thefollowing steps.

A ceramic part 20 made of silicon carbide ceramics, a metal part 30 madeof brass, and an intermediate layer 40 are provided. In this exemplaryembodiment, types of the brass may comprise alpha brass, alpha-betabrass, beta brass, lead brass containing 1 wt %˜6 wt % lead, tin brasscontaining 1 wt %˜6 wt % tin, aluminum brass containing 1 wt %˜6 wt %aluminum, manganese brass containing 1 wt %˜6 wt % manganese, iron brasscontaining 1 wt % 6 wt % iron, silicone silicon brass containing 1 wt%˜6 wt % silicone silicon, or nickel brass containing 1 wt %˜6 wt %nickel. The intermediate layer 40 connects together the surfaces of themetal part 30 and the ceramic part 20. The intermediate layer 40 mayinclude an aluminum foil 41 and a nickel foil 43 stacked on the aluminumfoil 41. The aluminum foil 41 is adjacent to the ceramic part 20 and thenickel foil 43 is adjacent the metal part 30. Each of the aluminum foil41 and the nickel foil 43 has a thickness of about 0.1 mm˜0.5 mm, suchas about 0.1 mm, 0.15 mm, 0.25 mm, 0.35 mm, 0.4 mm, or 0.5 mm . . . .

The metal part 30, ceramic part 20, and intermediate layer 40 arepretreated. The pretreatment may include polishing the surfaces of themetal part 30, ceramic part 20, and intermediate layer 40, by a 600grit˜1000 grit abrasive paper. Then, the metal part 30, ceramic part 20,and intermediate layer 40 may be activated through a cleaning processwith a solution containing hydrochloric acid or sulphuric acid. Then,the metal part 30, ceramic part 20, and intermediate layer 40 are rinsedwith water and dried.

A mold 50 made of electroconductive material, such as graphite, isprovided as shown in FIG. 1. The mold 50 includes an upper pressing head51, a lower pressing head 52, and a middle part 53. The middle part 53defines a cavity (no shown) for accommodating the parts to be joined.

Subsequently, the metal part 30, ceramic part 20, and intermediate layer40 are placed into the mold 50 with the intermediate layer 40 insertedbetween the metal part 30 and the ceramic part 20, the aluminum foil 41contacts the ceramic part 20 and the nickel foil 43, and the nickel foil43 contacts the metal part 30 and the aluminum foil 41. The upperpressing head 51 and the lower pressing head 52 from two opposite sidescompress the metal part 30, ceramic part 20, and intermediate layer 40together.

A SPS device 10 is provided. The SPS device 10 includes a pressuresystem 11 for providing pressure to the parts to be joined, a sinteringchamber 13, and a DC pulse power 14 for providing pulse current to theparts and heating up the parts. The DC pulse power 14 includes apositive electrode 16 and a negative electrode 17. The pulse-width ratioof the DC pulse power 14 is 6:1, and the maximum amps of the DC pulsepower 14 is 8000 A.

The mold 50 is placed in the sintering chamber 13. The upper pressinghead 51 and the lower pressing head 52 are electrically connected to thepositive electrode 16 and negative electrode 17 of the DC pulse power14. The sintering chamber 13 is evacuated to a vacuum level betweenabout 6 Pa and about 10 Pa. A pressure between about 10 MPa and 40 MPa,such as 10 MPa, 15 MPa, 20 MPa, 30 MPa, 35 MPa or 40 MPa, is thenapplied to the parts through the upper pressing head 51 and the lowerpressing head 52. While the g pressure is applied, a pulse electriccurrent between about 1000 A and 8000 A with a pulse-width ratio of 6:1is simultaneously applied to the parts, heating the parts at a rate lessthan 50 degrees Celsius per minute (° C./min) when the temperature ofthe parts are less than about 300° C., and heating the parts at a rateof about 80° C./min˜° C./min 200° C./min when the temperature of theparts are above about 300° C. The temperature of the parts aremaintained at about 550° C. to about 650° C., for about 15 minutes and40 minutes, such as 15 minutes, 20 minutes 30 minutes or 40 minutes.Under the above mentioned conditions, particles of the metal part 30,ceramic part 20, and intermediate layer 40 will react and fuse with eachother to form a joining part 80 (shown in FIG. 2) having multiplebetween the metal part 30 and the ceramic part 20. Thereby, the metalpart 30 and the ceramic part 20 are joined via the intermediate layer40, forming a composite article 100.

Once the composite article 100 is cooled down, the composite article 100can be removed.

Owing to the present process, a permanent joining part 80 of greatstrength is obtained. The process requires a short hold time and a lowvacuum level of the sintering chamber 13, thus significantly saves timeand energy. The aluminum foil 41 has a low melting point, so thealuminum foil 41 can be melted when the parts are heated, causing thealuminum foil 41 and the ceramics part 20 be fused together.Additionally, coefficients of thermal expansion of the ceramic part 20,aluminum foil 41, nickel foil 43, metal part 30 are gradually increased,i.e., a coefficient of thermal expansion of the intermediate layer 40 isbetween the coefficient of thermal expansion of the ceramics part 20 andthe coefficient of thermal expansion of the metal part 30 and graduallychanges from a value close to that of the ceramic part 20 in the area ofthe bond of the ceramic part 20 and the joint part 80 to a value closeto that of the metal part 30 in the area of the bond of the joint part80 with the metal part 30. Thus, thermal stress between the ceramicspart 20 and metal part 30 can be reduced by the intermediate layer 40thereby improving the binding force between the ceramics part 20 andmetal part 30 so the ceramics part 20 can be firmly joined with themetal part 30.

FIG. 2 shows a composite article 100 manufactured by the presentprocess. The composite article 100 includes the metal part 30, theceramic part 20, and a multi-layered joining part 80 joining the metalpart 30 and the ceramic part 20. The various layers of the joining layer80 result from differing interaction between the metal part 30, aluminumlayer 82, nickel layer 84, and ceramic part 20. In particular, thejoining layer 80 includes:

a) a first transition layer 81: The first transition layer 81 is locatedbetween the ceramics layer 20 and the aluminum layer 82. The firsttransition layer 81 mainly includes compounds composited aluminumelement and carbon element, such as aluminum carbide, and compoundscomposited aluminum element and silicon element, such as aluminumsilicide, etc. This chemical results result from chemical reactionsbetween adjacent portions of the ceramics layer 20 and aluminum layer82;

b) an aluminum layer 82: The aluminum layer 82 results from portions ofthe aluminum layer 82 that do not react with either the ceramics layer20 or the nickel layer 84;

c) a second transition layer 83: The second transition layer 83 islocated between the nickel layer 84 and the aluminum layer 82. Thesecond transition layer 83 mainly includes chemical compounds comprisingnickel element and aluminum element, and of nickel with aluminum solidsolutions. The chemical results result from chemical reactions betweenadjacent portions to the aluminum layer 82 and the nickel layer 84;

d) a nickel layer 84: The nickel layer 84 results from portions of thenickel layer 84 that do not react with either the aluminum layer 82 orthe ceramic part 20;

e) a third transition layer 85: The third transition layer 85 is locatedbetween the nickel layer 84 and the metal part 30. The third transitionlayer 85 mainly includes nickel with copper solid solutions, andchemical compounds comprising nickel element and copper element. Thechemical results result from chemical reactions between adjacentportions to the nickel layer 84 and the metal part 30.

The thermal expansion rate of the joining layer 80 gradually changesfrom a value close to that of the ceramic part 20 (in the area of 81) toa value close to that of the metal part 30 (in the area of 85). Thisresults in a composite article well suited to temperature changes due tothe gradual, rather than abrupt, changes in its internal thermalexpansion rates.

Furthermore, the joining part 80 of the composite article 100 has nocrack or aperture, and has a smooth surface. The metal/ceramic interfaceof the composite article 100 has a shear strength between about 20 MPaand 40 MPa, and a tensile strength between about 30 MPa and 60 MPa.

It is to be understood, however, that even through numerouscharacteristics and advantages of the exemplary disclosure have been setforth in the foregoing description, together with details of the systemand function of the disclosure, the disclosure is illustrative only, andchanges may be made in detail, especially in matters of shape, size, andarrangement of parts within the principles of the disclosure to the fullextent indicated by the broad general meaning of the terms in which theappended claims are expressed.

What is claimed is:
 1. A composite article, comprising: a metal partmade of brass; a ceramic part made of silicon carbide ceramic; and ajoining part, the joining part including a first transition layer, analuminum layer, a second transition layer, a nickel layer and a thirdtransition layer; the first transition layer located between the ceramicpart and the aluminum layer, the first transition layer substantiallycomprised of compounds of aluminum and carbon, and compounds of aluminumand silicon; the second transition layer located between the nickellayer and the aluminum layer, the second transition layer substantiallycomprised of intermetallic compounds of nickel and aluminum, and solidsolutions of nickel and aluminum; the third transition layer locatedbetween the nickel layer and the metal part, the third transition layersubstantially comprised of solid solutions of nickel and copper, andintermetallic compounds of nickel and copper.
 2. The composite articleas claimed in claim 1, wherein the metal/ceramic interface of thecomposite article has a shear strength between 20 MPa and 40 MPa.
 3. Thecomposite article as claimed in claim 1, wherein the metal/ceramicinterface of the composite article has a tensile strength between about30 MPa and 60 MPa.